The invention relates to an apparatus and a method for generating information on at least one characteristic of a fiber rope in the tobacco-processing industry, in particular a tobacco rope.
German patent document No. 38 01 115 C2 and corresponding U.S. Pat. No. 4,865,054 disclose a method and an apparatus for determining the density of a fiber rope. According to these documents, a nuclear measuring head generates a first density signal and an optical measuring head, in particular an infrared measuring head, generates a second density signal, which signals are used to remove undesirable influences, such as type and color of the tobacco for the fiber rope.
A method and an apparatus for detecting and localizing malfunctions in cigarette-producing machines are disclosed in German patent document 28 42 461 C2 and corresponding U.S. Pat. No. 4,280,187, wherein test signals generated by a nuclear measuring head are monitored for the appearance of different, characteristic signal components, which are respectively assigned to a specific machine element. Several test signals can be evaluated for this and related to each other.
German patent document 39 17 606 A1 and corresponding U.S. Pat. No. 4,967,739 disclose a method and an apparatus for producing cigarettes in which a density measuring signal and at least one additional measuring signal indicating another characteristic of the tobacco rope are correlated. From these selected cigarette characteristics tractive resistance, burnxcx9cdown time, nicotine content, condensate content, carbon monoxide content and rope hardness are displayed.
German patent document 197 05 260 A1 and corresponding U.S. Pat. No. 6,163,158 disclose a method and an apparatus for detecting at least one characteristic of a material, particularly the humid weight and/or the dry weight of tobacco, by evaluating detuning, due to the presence of the material, of a high-frequency resonator supplied with microwaves from a respective radiation source. Based on this, a high-frequency signal is produced, which is influenced by the material. The resonance frequency displacement and attenuation of this signal relative to a reference signal that is not influenced by the material are detected, so that the material characteristic can be determined from this.
U.S. Pat. No. 4,638,817 describes a tobacco feed control with two radiometric density sensors. A differential signal is formed from the signals generated by these two sensors and an alarm signal is generated if the differential signal exceeds a limit value considered normal.
European Patent Application No. 0 339 250 B1 and corresponding U.S. Pat. No. 4,920,987 disclose a system for controlling the tobacco filling amount in a cigarette production machine, provided with a first radiometric density measuring device in front of a trimmer and second radiometric density measuring device at a location where the previously wrapped tobacco rope passes by. The system further includes an advancing control and an automatic control circuit, for which the trimmer serves as adjustment member.
Finally, European Patent Application No. 0 793 425 B1 and corresponding U.S. Pat. No. 5,582,192 discloses a method and a device for diagnosing mechanical problems during the cigarette production. For this, a weight sensor is provided that emits signals, which can be used to generate error messages with a Fast Fourier Frequency Analysis, showing a possible abnormal state.
It is an object of the present invention to provide a method and an apparatus of the aforementioned type, which make it possible to obtain information on the fiber structure and in particular on deviations from an average fiber structure.
The above and other objects are accomplished in accordance with the invention by the provision of solved according to the invention with an apparatus comprising a first measuring device for generating a first measuring signal, which essentially only indicates the density of the fiber rope and a second measuring device for generating a second measuring signal, which essentially shows only a function of fiber rope density and fiber geometry. The apparatus also comprises an evaluation unit that uses the results of the first and second measuring signals to generate an evaluation signal providing information on the fiber structure, in particular on deviations from an average fiber structure.
The object is furthermore solved with a method for generating a first measuring signal that essentially only indicates the density of the fiber rope, a second measuring signal that essentially represents a function of fiber rope density and fiber geometry. The method is also used to generate an evaluation signal on the basis of the first and second measuring signals, which provides information on the fiber structure, in particular on the deviations from an average fiber structure.
For reasons of completeness, it must be mentioned here that the terms xe2x80x9cmeasuring signalxe2x80x9d and xe2x80x9cevaluation signalxe2x80x9d also can be understood as measuring value or result value.
The invention provides information on the fiber structure and in particular the deviations from an average structure of a fiber rope. According to the invention, this is achieved by relating a first measuring signal that essentially only indicates the density of the fiber rope to a second signal that represents a function of fiber density and fiber geometry, such that the density is blanked out and an evaluation signal is obtained, which is essentially determined by the fiber geometry, from which the fiber structure can be inferred. From this, it can be inferred whether specific machine parts on a tobacco-rope production line are worn and, in particular, whether irregularities exist at the feeder, as well as abnormal tobacco destruction in the conveying lines and/or abnormal tobacco end mixtures and/or tobacco destruction in the distributor. In particular deviations from an average fiber structure value lead to the conclusion of at least one of the aforementioned malfunctions.
It is advantageous if beta and/or microwave radiation that penetrates the fiber rope is transmitted from a first radiation source and, following the penetration, is picked up by a first sensor that generates a first measuring signal, which essentially only provides the density of the fiber rope. Thus, a first measuring signal is generated at the fiber rope for the density of the fiber rope with beta and/or microwave radiation. For at least some of the previously mentioned known methods and apparatuses, this signal has until now served as basis for a weight adjustment.
A second radiation source furthermore emits an infrared radiation that penetrates the fiber rope and is picked up by a second sensor, which generates from this a second measuring signal representing a function of fiber rope density and fiber geometry. Thus, the second measuring signal is generated through absorption of infrared light by the fiber rope The second measuring signal gained through the infrared light absorption, however, depends not only on the density, but also to a high degree on the fiber geometry and in particular the fiber length. In the final analysis, the weight adjustment on the basis of the infrared light absorption failed because of this dependence on the structure. However, since the weight must not be detected and adjusted for the present case, but information on the fiber structure is desired, it is of particular use to the invention that the infrared absorption also depends on the fiber geometry. According to the invention, the desired evaluation signal that is essentially determined only by the fiber geometry is obtained from the infrared light absorption by linking it to the first measuring signal, which only provides the density of the fiber rope and thus is an essentially xe2x80x98purexe2x80x99 density signal.
A malfunction in the process sequence can be inferred if this evaluation signal falls below or exceeds a limit value considered normal. In that case, the evaluation device advantageously transmits a corresponding warning signal. The locations of malfunctions can be narrowed down further with the aid of additional embodiments.
The difference between the first and second measuring signal is advantageously determined for generating an evaluation signal. Thus, the fiber geometry is determined by forming the differential value between the first measuring signal, essentially representing a pure density signal, and the second measuring signal that depends on the density as well as the structure.
The first and second measuring devices can be arranged one behind the other along the conveying path for the fiber rope, wherein the order in which they are arranged is basically optional. The first and second measuring signals for this exemplary embodiment consequently are determined at the finished fiber rope.
It is also conceivable that the second measuring signal is determined on a suction rope conveyor, behind the trimmer of a production line for processing a tobacco rope.
The first measuring signal that essentially only provides the density can preferably also be used as an actual value for a control system to adjust the weight of the fiber rope to be produced.
Another preferred embodiment of the invention with a device for producing the fiber rope and a subsequent device for conveying and wrapping the produced fiber rope, is distinguished by a third measuring device in the production apparatus. This third measuring device generates a third measuring signal, preferably at its output, which essentially only indicates the fiber rope density. This embodiment furthermore is distinguished in that the first and second measuring devices are arranged along the conveying device, downstream of the location where the fiber rope is wrapped, and that the evaluation device additionally uses the third measuring signal. According to a modification of this embodiment, infrared radiation can be used to generate the third measuring signal.
Finally, a system comprising several of the above-described apparatuses along with a central comparator can be provided, to which the evaluation devices are connected. To be sure, it several cigarette-production machines are supplied by a single feeder, it is possible to detect unfavorable conditions in one or the other conveying line or wear on the machine parts by detecting and comparing the structure of the tobacco in the tobacco ropes and cigarette ropes in the machines. In a double-rope machine, for example, a comparison of the two ropes can lead to a conclusion that an abnormal end mixture or abnormal tobacco destruction on a tobacco path exist, for example through wear of the structural components. Furthermore, a comparison between different machines supplied by the same feeder can lead to the conclusion that the momentarily produced tobacco mixture no longer meets the standard if all machines show approximately the same deviation. The same conclusion of a malfunction on the path from the feeder to the cigarette machine can be reached if only one of the machines shows a deviation that results, for example, from an erroneous adjustment or a worn structural component.